CN110364606A - A kind of epitaxial structure of ultraviolet light-emitting diode and its manufacturing method - Google Patents

Abstract

The invention discloses an ultraviolet light-emitting diode epitaxial structure and a manufacturing method thereof. The epitaxial structure includes an AlN layer, an N-type AlGaN layer, an active layer, a P-type superlattice barrier layer, and a P-type AlGaN layer sequentially arranged on a substrate. GaN layer, the P-type superlattice barrier layer is alternately formed by the first undoped layer, the first Mg layer, the second undoped layer and the second Mg layer, the content of Al in the first undoped layer is the same as The content of Al in the second non-doped layer varies. In the present invention, a P-type superlattice barrier layer is arranged between the active layer and the P-type GaN layer, which not only blocks the current and improves the current expansion, but also improves the hole concentration and migration of the P-type GaN layer. Efficiency, providing more hole-electron pairs for the active layer, increasing the probability of recombination, improving the brightness, thereby improving the photoelectric performance of the epitaxial structure.

Description

A kind of epitaxial structure of ultraviolet light-emitting diode and its manufacturing method

technical field

The invention relates to the technical field of light emitting diodes, in particular to an epitaxial structure of an ultraviolet light emitting diode and a manufacturing method thereof.

Background technique

AlGaN semiconductor material has a very wide direct bandgap, and the forbidden band width is continuously adjustable from 3.4 to 6.2eV, making its photoresponse band cover from near ultraviolet (UVA) to deep ultraviolet (UVC). Compared with traditional ultraviolet light sources, such as mercury lamps and xenon lamps, ultraviolet LEDs have the advantages of no mercury pollution, controllable wavelength, small size, low power consumption, and long life. Curing, sterilization, medical and sanitation, water and air purification, high-density optical data storage and other fields have broad application prospects and huge market demand.

Compared with the mature GaN-based blue light epitaxial structure, the luminous efficiency of the ultraviolet light-emitting diode epitaxial structure is generally low, and the luminous efficiency drops sharply with the decrease of the wavelength.

In the existing UV light-emitting diode epitaxial structure, since the activation energy of the Mg acceptor increases with the increase of the Al composition, the Mg doping concentration of the p-layer decreases and the activation efficiency decreases under the high Al composition, thereby reducing the epitaxial structure. Luminous efficiency. In addition, the crystal quality of the epitaxial structure is poor, and Mg is easy to cluster together to form impurity centers, which is not conducive to the increase of doping concentration. How to prepare a UV light-emitting diode epitaxial structure with good crystal quality and high luminous power is an urgent problem to be solved at present.

Contents of the invention

The technical problem to be solved by the present invention is to provide an epitaxial structure of an ultraviolet light emitting diode, increase the doping concentration of the p layer, and improve the luminous efficiency of the epitaxial structure.

The invention also provides a method for manufacturing the epitaxial structure of the ultraviolet light emitting diode, which has simple process and low cost.

In order to solve the above problems, the present invention provides an epitaxial structure of an ultraviolet light-emitting diode, comprising an AlN layer, an N-type AlGaN layer, an active layer, a P-type superlattice barrier layer and a P-type GaN layer sequentially arranged on a substrate, The P-type superlattice barrier layer is formed alternately by the first undoped layer, the first Mg layer, the second undoped layer and the second Mg layer, and the content of Al in the first undoped layer is the same as that of the second undoped layer. The content of Al in the doped layer varies.

As an improvement of the above solution, the first undoped layer is made of Al _u Ga _1-u N, 0≤u≤1; the second undoped layer is made of Al _v Ga _1-v N, 0≤v≤1, u≠v.

As an improvement of the above solution, u>v.

As an improvement of the above solution, the doping concentration of Mg in the P-type superlattice barrier layer is 8-10E18atom/cm ³ .

As an improvement of the above scheme, the P-type superlattice barrier layer is made by the following method:

(1) feed a nitrogen source with a flow rate of 65-75 slm, an aluminum source with a flow rate of 180-210 sccm, and a gallium source with a flow rate of 28-33 sccm, and grow a first non-doped layer with a thickness of 0-20 nm;

(2) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm, and continue for 0 to 10 minutes to form the first Mg layer;

(3) Turn off the magnesium source, feed a nitrogen source with a flow rate of 65-75 slm, an aluminum source with a flow rate of 180-210 sccm, and a gallium source with a flow rate of 28-33 sccm, and grow a second non-doped layer with a thickness of 0-20 nm;

(4) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm for 0 to 10 minutes to form a second Mg layer;

(5) Repeat steps (1), (2), (3) and (4) several times.

As an improvement of the above scheme, a transition layer is provided between the AlN layer and the N-type AlGaN layer; the transition layer is composed of several periods of AlN/Al _a Ga _1-a N (0.01<a<0.99) supercrystal Composition of a lattice structure; the thickness of AlN in the AlN/Al aGa _1-a N superlattice structure is 1-5 nm, and the thickness of Al _a Ga _{1-a N} is 1-5 nm.

As an improvement of the above solution, the active layer is composed of several periodic quantum well structures, the quantum well structure includes Al _x Ga _1-x N well layer and A _y Ga _1-y N barrier layer, 0<x <0.5, y is more than 20% larger than x;

The thickness of the AlxGa1 _{- xN} well layer is 3-8nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 4-10nm.

As an improvement of the above solution, in the N-type AlGaN layer, the Si doping concentration is 5E17˜5E19 atom/cm ³ , and the thickness is 0.5˜2 μm.

As an improvement of the above solution, in the P-type GaN layer, the Mg doping concentration is 1E17˜1E21 atom/cm ³ , and the thickness is 0˜200 nm.

Correspondingly, the present invention also provides a method for fabricating an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 900-1500°C for 1-20 minutes;

2. Adjust the temperature to 900-1500°C, and form an AlN layer with a thickness of 0.1-5 μm on the substrate;

3. Adjust the temperature to 900-1500° C., and form an N-type AlGaN layer with a thickness of 0.5-2 μm on the AlN layer, and a Si doping concentration of 5E17-5E19 atom/cm ³ ;

4. Adjust the temperature to 900-1500°C, and grow several periods of quantum well structures on the N-type AlGaN layer. The quantum well structures include Al _x Ga _1-x N well layers and A _y Ga _1-y N barriers layer, 0<x<0.5, 0.2<y<1, the thickness of the Al _x Ga _1-x N well layer in each quantum well structure is 3-8 nm, and the thickness of the Aly Ga _{1-y N} barrier layer is 4-8 nm. 10nm;

5. Adjust the temperature to 900-1500°C, (1) feed nitrogen source, aluminum source, and gallium source to grow the first non-doped layer with a thickness of 0-20nm; (2) turn off the aluminum source and gallium source, and pass Inject nitrogen source and magnesium source for 0-10 minutes to form the first Mg layer; (3) turn off the magnesium source, feed nitrogen source, aluminum source, and gallium source, and grow a second non-doped layer with a thickness of 0-20nm ; (4) close aluminum source and gallium source, pass into nitrogen source and magnesium source, continue 0～10 minutes, form the second Mg layer; (5) repeat steps (1), (2), (3) and (4 ) several times to form a P-type superlattice barrier layer;

6. Adjust the temperature to 900-1500° C., and form a P-type GaN layer with a thickness of 0-200 nm on the P-type superlattice barrier layer, and a Mg doping concentration of 1E17-1E21 atom/cm ³ .

Implement the present invention, have following beneficial effect:

The epitaxial structure of an ultraviolet light-emitting diode provided by the present invention comprises an AlN layer, an N-type AlGaN layer, an active layer, a P-type superlattice barrier layer and a P-type GaN layer sequentially arranged on a substrate. In the present invention, a P-type superlattice barrier layer is arranged between the active layer and the P-type GaN layer, which not only blocks the current and improves the current expansion, but also improves the hole concentration and migration of the P-type GaN layer. The efficiency provides more hole-electron pairs for the active layer, increases the probability of recombination, improves the brightness, and thus improves the photoelectric performance of the epitaxial structure.

The P-type superlattice barrier layer is formed alternately by the first undoped layer, the first Mg layer, the second undoped layer and the second Mg layer, and the content of Al in the first undoped layer is the same as that of the second undoped layer. The content of Al in the doped layer is different. The first non-doped layer and the second non-doped layer of the present invention do not introduce Mg impurities, do not form stacking dislocations, effectively improve the crystal quality of the P-type GaN layer, and reduce the dislocation density, while Mg doped The injection is after the formation of the first undoped layer and the second undoped layer, so the Mg atoms can freely choose the best position for doping, thereby reducing the self-compensation effect, increasing the hole concentration of the P-type GaN layer and its mobility.

The doping concentration of Mg in the P-type superlattice barrier layer of the present invention can reach 8-10E18atom/cm ³ .

Description of drawings

Fig. 1 is a structural schematic diagram of the epitaxial structure of the present invention;

Fig. 2 is a structural schematic diagram of another embodiment of the epitaxial structure of the present invention;

Fig. 3 is the growth process figure of P-type superlattice barrier layer of the present invention;

Fig. 4 is the growth process figure of existing electron blocking layer of the present invention;

FIG. 5 is a comparison chart of Mg doping concentration in Comparative Example 1 and Example 3 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, a kind of ultraviolet light-emitting diode epitaxial structure provided by the present invention comprises AlN layer 20, N-type AlGaN layer 30, active layer 40, P-type superlattice barrier layer 50 and P type GaN layer 60.

The material of the substrate 10 of the present invention may be sapphire, silicon carbide or silicon, or other semiconductor materials. Preferably, the substrate 10 of the present invention is a sapphire substrate.

The AlN layer 20 of the present invention is made of AlN, and as the base material of the epitaxial structure, its function is to prepare for the subsequent growth of the N-type AlGaN layer 30 , the active layer 40 and the P-type GaN layer 60 . Since the energy level of AlN is the largest in the III/V group system, and the light absorption to LED is the smallest, using AlN as the basic material can effectively improve the light extraction efficiency of the epitaxial structure.

Preferably, the thickness of the AlN layer 20 is 2-4 μm. If the thickness of the AlN layer 20 is less than 2 μm, the stress mismatch between the substrate and the AlN material cannot be fully released, affecting the crystal quality of the AlN material; if the thickness is too thick, time and materials will be wasted.

Due to the large lattice difference between the AlN layer 20 and the N-type AlGaN layer 30 , if the N-type AlGaN layer is directly grown on the AlN layer, cracks will be caused due to stress accumulation at the interface between the two materials. Referring to FIG. 2, as another preferred solution of the present invention, the present invention forms a transition layer 21 between the AlN layer 20 and the N-type AlGaN layer 30, so as to gradually release the stress caused by lattice mismatch in the transition layer 21, In this way, the problem of cracks in the AlN layer is avoided, the quality of the AlN layer is improved, and dislocations and defects are greatly reduced, thereby improving the crystal quality of the epitaxial structure, thereby improving the luminous efficiency. In addition, lower dislocations and defects in epitaxial materials mean fewer photon capture centers, which is beneficial for more ultraviolet light to pass through the epitaxial structure, improving light extraction efficiency, and reducing the total amount of photons generated after being captured. The heat greatly improves the performance of the purple LED device.

Preferably, the transition layer has a thickness of 200-400 nm. If the thickness of the transition layer is less than 200 nm, the stress and dislocation cannot be well released, and if the thickness is too thick, time and materials will be wasted.

Since the AlN/Al _a Ga _1-a N superlattice structure can well release the stress between the AlN material and the N-type AlGaN, and the AlN/Al _a Ga _1-a N superlattice structure can bend the dislocation line , so as to achieve the purpose of improving the crystal quality. Specifically, the transition layer 21 is composed of several periodic AlN/Al _{aGa 1-a} N (0.01<a<0.99) superlattice structures.

In the AlN/Al _a Ga _1-a N superlattice structure, the value of a is greater than the Al content in the N-type AlGaN layer and less than 0.8. If a is greater than 0.8, the transition layer cannot release the stress well. If a is less than the Al content in the N-type AlGaN layer, a light absorption effect will occur, which is not conducive to light transmission from the epitaxial surface.

The thickness of AlN in the AlN/Al _a Ga _1-a N superlattice structure is 1-5 nm, and the thickness of Al _a Ga _1-a N is 1-5 nm. Preferably, the thickness of each AlN/Al _a Ga _1-a N superlattice structure is 2 to 10 nm. Since its thickness is several atomic layers thick, the AlN/Al _a Ga _1-a N superlattice structure Best for stress relief and dislocation reduction.

In order to improve the light extraction efficiency of the active layer 40, the present invention makes a special design for the structure of the active layer. The active layer 40 is composed of 3 to 5 periods of quantum well structure, the quantum well structure includes AlxGa1 _{- xN} well layer and _{AlyGa1 -yN} barrier layer, 0<x<0.5, 0.2<y<1.

It should be noted that too few quantum wells cannot completely confine electron and hole pairs and affect brightness; due to the limited migration distance of holes, too many quantum well cycles will not improve brightness, but time and raw material costs will increase.

Since the luminescent wavelength of the epitaxial structure is determined by x in the quantum well structure, the violet wavelength of the ultraviolet LED chip in the market is distributed around 260-365nm, and the corresponding Al composition is 0-50%, that is, 0<x<0.5. In order to better limit the luminescence of electron-hole pairs in the quantum well structure, y needs to be larger than x by more than 20%.

The thickness of the AlxGa1 _{- xN} well layer is 3-8nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 4-10nm. If the thickness of the AlyGa _{1-y N} barrier layer is too thin, it is not conducive to the binding of electron-hole pairs, and if it is too thick, it is not conducive to the migration of holes.

The N-type AlGaN layer 40 of the present invention is used to provide electrons, and the P-type AlGaN layer 60 is used to provide holes. In order to improve the light extraction efficiency of the epitaxial structure, the thickness of the N-type AlGaN layer is 0.5-2 μm, and the Si doping concentration is 5E17-5E19 atom/cm ³ . In the P-type GaN layer, the Mg doping concentration is 1E17˜1E21 atom/cm ³ , and the thickness is 0˜200 nm.

In the present invention, a P-type superlattice barrier layer 50 is arranged between the active layer 40 and the P-type GaN layer 60, which not only blocks the current and improves the current expansion, but also increases the hole concentration of the P-type GaN layer. And its mobility, provide more hole-electron pairs for the active layer, increase the probability of recombination, increase the brightness, and thus improve the photoelectric performance of the epitaxial structure.

The P-type superlattice barrier layer of the present invention is alternately formed by the first undoped layer, the first Mg layer, the second undoped layer and the second Mg layer, and the content of Al in the first undoped layer is the same as that of the second The content of Al in the non-doped layer varies. The first non-doped layer and the second non-doped layer of the present invention do not introduce Mg impurities, do not form stacking dislocations, effectively improve the crystal quality of the P-type GaN layer, and reduce the dislocation density, while Mg doped The injection is after the formation of the first undoped layer and the second undoped layer, so the Mg atoms can freely choose the best position for doping, thereby reducing the self-compensation effect, increasing the hole concentration of the P-type GaN layer and its mobility.

The first undoped layer is made of Al _u Ga _1-u N, 0≤u≤1; the second undoped layer is made of Al _v Ga _1-v N, 0≤v≤1, u≠v. The content of Al in the first non-doped layer must be different from the content of Al in the second non-doped layer, so as to produce a difference in potential and to bend the energy band of the P-type superlattice barrier layer. The invention increases the doping concentration of Mg by changing the energy band bending of the P-type superlattice barrier layer to form the first Mg layer and the second Mg layer, thereby increasing the hole concentration and mobility of the P-type GaN layer. Preferably, u>v.

Specifically, the first undoped layer is made of AlGaN, and the second undoped layer is made of AlN. Alternatively, the first undoped layer is made of AlN, and the second undoped layer is made of AlGaN. In other embodiments of the present invention, the first undoped layer is made of AlN, and the second undoped layer is made of GaN. Alternatively, the first undoped layer is made of AlGaN, and the second undoped layer is made of GaN.

The Mg doping concentration of the P-type superlattice barrier layer of the present invention can reach 8-10E18atom/cm ³ , while the Mg doping concentration of the existing electron blocking layer is only 1E18atom/cm ³ , and the hole activation efficiency of Mg is generally The Mg doping concentration is about 1%, and the higher the doping concentration, the easier it is to excite holes.

The thickness of the first non-doped layer is 1-20 nm, and the thickness of the second non-doped layer is 1-20 nm. Preferably, the thickness of the first non-doped layer is 2-6 nm, and the thickness of the second non-doped layer is 2-6 nm. The present invention improves the doping concentration by changing the energy band bending of the P-type superlattice barrier layer, and the thickness of the first non-doped layer or the second non-doped layer is too thin or too thick to cause superlattice layer The piezoelectric polarization is weakened, which reduces the energy band bending, which is not conducive to the doping of Mg.

Referring to Fig. 3, P-type superlattice barrier layer of the present invention is made by following method:

(1) feed a nitrogen source with a flow rate of 65-75 slm, an aluminum source with a flow rate of 180-210 sccm, and a gallium source with a flow rate of 28-33 sccm, and grow a first non-doped layer with a thickness of 0-20 nm;

(2) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm, and continue for 0 to 10 minutes to form the first Mg layer;

(3) Turn off the magnesium source, feed a nitrogen source with a flow rate of 65-75 slm, an aluminum source with a flow rate of 180-210 sccm, and a gallium source with a flow rate of 28-33 sccm, and grow a second non-doped layer with a thickness of 0-20 nm;

(4) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm for 0 to 10 minutes to form a second Mg layer;

(5) Repeat steps (1), (2), (3) and (4) several times.

It should be noted that the nitrogen source is preferably NH ₃ , the aluminum source is TMAl, the gallium source is TMGa, and the magnesium source is Cp ₂ Mg. Preferably, the flow rate of the gallium source in step (3) is smaller than the flow rate of the gallium source in step (1).

Referring to Fig. 4, existing barrier layer is to pass into nitrogen source, aluminum source, gallium source and magnesium source simultaneously, there will be the competitive relationship that Mg element, Al element, Ga element combine with N element simultaneously, the present invention is in step (2 ) and (4), only the nitrogen source and the magnesium source are introduced to form the first Mg layer and the second Mg layer, so there is no competition, and the doping efficiency of the Mg element will be improved.

In the process of growing the first non-doped layer and the second non-doped layer using the discontinuous doping method of the present invention, since there is no introduction of Mg impurities, stacking dislocations will not be formed, thereby improving the P-type superlattice barrier layer. Crystal quality and improve the crystal quality of the P-type GaN layer, reduce the dislocation density, and the doping of Mg is to form the first Mg layer and the second Mg layer after the formation of the first undoped layer and the second undoped layer, respectively. layer, so Mg atoms can freely choose the best position for doping, thereby reducing the self-compensation effect and increasing the hole concentration and mobility of the P-type GaN layer.

In addition, the discontinuous doping method of the present invention utilizes the difference in potential between _{AluGa1 -} uN and _{AlvGa1 -} vN to promote the energy band bending of the P-type superlattice barrier layer. The invention increases the doping concentration of Mg by changing the energy band bending of the P-type superlattice barrier layer, thereby increasing the hole concentration and mobility of the P-type GaN layer.

It should be noted that the present invention increases the doping concentration by improving the material quality of the P-type superlattice barrier layer and improving its energy band structure so that most of the Mg impurities are located below the Fermi level.

In order to obtain a band-bending P-type superlattice barrier layer, the content of the Al component in step (1) and step (3) cannot be the same. Since the doping rates of Mg in AlGaN with different Al contents are different, the duration settings of step (2) and step (4) are also different. The higher the content of Al component, the harder it is for Mg to dope, and the longer it takes. If the content of the Al component in the step (1) is greater than the content of the Al component in the step (3), the duration in the step (2) is longer than that in the step (4).

Correspondingly, the present invention also provides a method for fabricating an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 900-1500°C for 1-20 minutes;

2. Adjust the temperature to 900-1500°C, and form an AlN layer with a thickness of 0.1-5 μm on the substrate;

3. Adjust the temperature to 900-1500° C., and form an N-type AlGaN layer with a thickness of 0.5-2 μm on the AlN layer, and a Si doping concentration of 5E17-5E19 atom/cm ³ ;

4. Adjust the temperature to 900-1500°C, and grow several periods of quantum well structures on the N-type AlGaN layer. The quantum well structures include Al _x Ga _1-x N well layers and A _y Ga _1-y N barriers layer, 0<x<0.5, 0.2<y<1, the thickness of the Al _x Ga _1-x N well layer in each quantum well structure is 3-8 nm, and the thickness of the Aly Ga _{1-y N} barrier layer is 4-8 nm. 10nm;

5. Adjust the temperature to 900-1500°C, (1) Introduce a nitrogen source with a flow rate of 65-75slm, an aluminum source with a flow rate of 180-210sccm, and a gallium source with a flow rate of 28-33sccm, and grow a film with a thickness of 0-20nm The first non-doped layer; (2) close the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm, and continue for 0 to 10 minutes to form the first Mg layer; ( 3) Turn off the magnesium source, feed a nitrogen source with a flow rate of 65-75 slm, an aluminum source with a flow rate of 180-210 sccm, and a gallium source with a flow rate of 28-33 sccm, and grow a second non-doped layer with a thickness of 0-20 nm; ( 4) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65 to 75 slm and a magnesium source with a flow rate of 950 to 1100 sccm for 0 to 10 minutes to form a second Mg layer; (5) repeat steps (1), (2), (3) and (4) several times;

6. Adjust the temperature to 900-1500° C., and form a P-type GaN layer with a thickness of 0-200 nm on the P-type superlattice barrier layer, and a Mg doping concentration of 1E17-1E21 atom/cm ³ .

Below will further illustrate the present invention with specific embodiment

Example 1

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 900°C for 20 minutes;

2. Adjust the temperature to 1000°C, and form an AlN layer with a thickness of 1 μm on the substrate;

3. Adjust the temperature to 900°C, and form an N-type AlGaN layer with a thickness of 0.5 μm on the AlN layer, with a Si doping concentration of 5E17atom/cm ³ ;

4. Adjusting the temperature to 1000° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1000° C., (1) feed a nitrogen source with a flow rate of 65 slm, an aluminum source with a flow rate of 180 sccm, and a gallium source with a flow rate of 30 sccm to grow a first non-doped layer with a thickness of 1 nm; (2) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 65slm and a magnesium source with a flow rate of 950sccm for 0.5 minutes to form the first Mg layer; (3) turn off the magnesium source, and feed a nitrogen source with a flow rate of 65slm Be the aluminum source of 180sccm, the gallium source that the flow rate is 28sccm, grow the second undoped layer that thickness is 1nm; (4) turn off the aluminum source and the gallium source, feed the nitrogen source that the flow rate is 65slm and the magnesium source that the flow rate is 950sccm , continue 0.5 minute, form the second Mg layer; (5) repeat steps (1), (2), (3) and (4) 8 times, form the P-type superlattice barrier layer;

6. Adjust the temperature to 1000° C., and form a P-type GaN layer with a thickness of 10 nm on the P-type superlattice barrier layer, and a Mg doping concentration of 1E17 atom/cm ³ .

Example 2

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 1000°C for 15 minutes;

2. Adjust the temperature to 1000°C, and form an AlN layer with a thickness of 1.5 μm on the substrate;

3. Adjust the temperature to 1100° C., and form an N-type AlGaN layer with a thickness of 1 μm on the AlN layer, and the Si doping concentration is 9E17 atom/cm ³ ;

4. Adjusting the temperature to 1000° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1100° C., (1) feed a nitrogen source with a flow rate of 70 slm, an aluminum source with a flow rate of 190 sccm, and a gallium source with a flow rate of 32 sccm, and grow a first non-doped layer with a thickness of 1.5 nm; (2 ) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 70slm and a magnesium source with a flow rate of 980sccm for 1 minute to form the first Mg layer; (3) turn off the magnesium source, and feed a nitrogen source with a flow rate of 70slm, Flow rate is the aluminum source of 190sccm, the flow rate is the gallium source of 30sccm, and the growth thickness is the second undoped layer of 1.5nm; (4) shut down the aluminum source and the gallium source, feed the nitrogen source that the flow rate is 70slm and the flow rate is the 980sccm Magnesium source, continue 1 minute, form the second Mg layer; (5) repeat step (1), (2), (3) and (4) 10 times, form P-type superlattice barrier layer;

6. Adjust the temperature to 1100° C., and form a P-type GaN layer with a thickness of 30 nm on the P-type superlattice barrier layer, with a Mg doping concentration of 5E17atom/cm ³ .

Example 3

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 1100°C for 10 minutes;

2. Adjust the temperature to 1300°C, and form an AlN layer with a thickness of 3 μm on the substrate;

3. Adjust the temperature to 1200°C, and form an N-type AlGaN layer with a thickness of 2 μm on the AlN layer, and the Si doping concentration is 2E18atom/cm ³ ;

4. Adjusting the temperature to 1100° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1100° C., (1) feed a nitrogen source with a flow rate of 70 slm, an aluminum source with a flow rate of 200 sccm, and a gallium source with a flow rate of 32 sccm to grow a first non-doped layer with a thickness of 2.5 nm; (2 ) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 70slm and a magnesium source with a flow rate of 1000sccm for 1.5 minutes to form the first Mg layer; (3) turn off the magnesium source, and feed a flow rate with a nitrogen source of 70slm, The aluminum source with the flow rate of 200sccm and the gallium source with the flow rate of 30sccm grow the second non-doped layer with a thickness of 2.5nm; Magnesium source, continue 1.5 minutes, form the second Mg layer; (5) repeat step (1), (2), (3) and (4) 10 times, form P-type superlattice barrier layer;

Sixth, adjust the temperature to 1000° C., and form a P-type GaN layer with a thickness of 50 nm on the P-type superlattice barrier layer, and a Mg doping concentration of 2E18atom/cm ³ .

Example 4

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 1200°C for 8 minutes;

2. Adjust the temperature to 1300°C, and form an AlN layer with a thickness of 4 μm on the substrate;

3. Adjust the temperature to 1200°C, and form an N-type AlGaN layer with a thickness of 2 μm on the AlN layer, with a Si doping concentration of 5E18atom/cm ³ ;

4. Adjusting the temperature to 1100° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1100° C., (1) feed a nitrogen source with a flow rate of 72 slm, an aluminum source with a flow rate of 200 sccm, and a gallium source with a flow rate of 33 sccm to grow a first non-doped layer with a thickness of 5 nm; (2) Turn off the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 75slm and a magnesium source with a flow rate of 1050sccm for 3 minutes to form the first Mg layer; (3) turn off the magnesium source, and feed a nitrogen source with a flow rate of 72slm Be the aluminum source of 200sccm, flow be the gallium source of 32sccm, grow the second non-doped layer that thickness is 5nm; (4) turn off aluminum source and gallium source, feed flow be the nitrogen source of 75slm and flow be the magnesium source of 1050sccm , continue 3 minutes, form the second Mg layer; (5) repeat step (1), (2), (3) and (4) 15 times, form P-type superlattice barrier layer;

6. Adjust the temperature to 1200° C., and form a P-type GaN layer with a thickness of 100 nm on the P-type superlattice barrier layer, with a Mg doping concentration of 5E18atom/cm ³ .

Example 5

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 1500°C for 5 minutes;

2. Adjust the temperature to 1400°C, and form an AlN layer with a thickness of 5 μm on the substrate;

3. Adjust the temperature to 1400° C., and form an N-type AlGaN layer with a thickness of 2 μm on the AlN layer, with a Si doping concentration of 5E19atom/cm ³ ;

4. Adjusting the temperature to 1300° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1300° C., (1) feed a nitrogen source with a flow rate of 75 slm, an aluminum source with a flow rate of 210 sccm, and a gallium source with a flow rate of 33 sccm to grow a first non-doped layer with a thickness of 10 nm; (2) Close the aluminum source and the gallium source, feed a nitrogen source with a flow rate of 75slm and a magnesium source with a flow rate of 1100sccm for 5 minutes to form the first Mg layer; Be the aluminum source of 210sccm, flow be the gallium source of 31sccm, grow the second non-doped layer that thickness is 10nm; (4) turn off aluminum source and gallium source, feed flow be the nitrogen source of 75slm and flow be the magnesium source of 1100sccm , continue 5 minutes, form the second Mg layer; (5) repeat step (1), (2), (3) and (4) 10 times, form P-type superlattice barrier layer;

6. Adjust the temperature to 1400° C., and form a P-type GaN layer with a thickness of 150 nm on the P-type superlattice barrier layer, with a Mg doping concentration of 5E19atom/cm ³ .

Comparative example 1

A method for manufacturing an epitaxial structure of an ultraviolet light-emitting diode, comprising the following steps:

1. Put the substrate into the MOCVD equipment and bake it at 1100°C for 10 minutes;

2. Adjust the temperature to 1300°C, and form an AlN layer with a thickness of 3 μm on the substrate;

3. Adjust the temperature to 1200°C, and form an N-type AlGaN layer with a thickness of 2 μm on the AlN layer, and the Si doping concentration is 2E19atom/cm ³ ;

4. Adjusting the temperature to 1100° C., growing five periods of quantum well structures on the N-type AlGaN layer, the quantum well structures including Al _x Ga _1-x N well layers and A _y Ga _1-y N barrier layers, x=0.4, y=0.6, the thickness of the AlxGa1 _{- xN} well layer in each quantum well structure is 3nm, and the thickness of the _{AlyGa1 -yN} barrier layer is 5nm;

5. Adjust the temperature to 1100°C, (1) feed nitrogen source, aluminum source, gallium source and magnesium source, and grow a barrier layer with a thickness of 50nm;

Sixth, the temperature is adjusted to 1000° C., and a P-type GaN layer with a thickness of 50 nm is formed on the barrier layer, and the Mg doping concentration is 2E20 atom/cm ³ .

Adopt the manufacturing method of embodiment 1 to embodiment 5 and comparative example 1 to make the same size chip, carry out photoelectric test, the result is as follows:

ID wavelength/nm Brightness/mW Voltage/V Comparative example 1 279.6 9.35 6.31 Example 1 279.5 11.11 6.02 Example 2 279.6 11.95 6.01 Example 3 279.5 12.68 5.98 Example 4 279.6 12.63 5.99 Example 5 279.6 12.62 6.02

Referring to Fig. 5, Fig. 5 is a comparative diagram of the Mg doping concentration of Comparative Example 1 and Example 3, the Mg doping concentration of the barrier layer of Example 3 is much higher than the Mg doping concentration of the barrier layer of Comparative Example 1 .

The above disclosure is only a preferred embodiment of the present invention, which certainly cannot limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims (10)

1. a kind of UV LED epitaxial structure, which is characterized in that including be sequentially arranged on substrate AlN layer, N-type AlGaN layer, active layer, p-type superlattices barrier layer and p-type GaN layer, p-type superlattices barrier layer is by the first non-doped layer, One Mg layers, the second non-doped layer and the 2nd Mg layers be alternatively formed, in the first non-doped layer in the content of Al and the second non-doped layer The content of Al differs.

2. UV LED epitaxial structure as described in claim 1, which is characterized in that first non-doped layer by Al_uGa_1-uN is made, 0≤u≤1；Second non-doped layer is by Al_vGa_1-vN is made, 0≤v≤1, u ≠ v.

3. UV LED epitaxial structure as claimed in claim 2, which is characterized in that u > v.

4. UV LED epitaxial structure as described in claim 1, which is characterized in that p-type superlattices barrier layer The doping concentration of middle Mg is 8~10E18atom/cm³。

5. UV LED epitaxial structure as described in claim 1, which is characterized in that p-type superlattices barrier layer It is made by following methods:

(1) being passed through silicon source, flow that nitrogen source, flow that flow is 65~75slm are 180~210sccm is 28~33sccm's Gallium source, growth thickness are the first non-doped layer of 0~20nm；

(2) silicon source and gallium source are closed, the nitrogen source that flow is 65~75slm and the magnesium source that flow is 950~1100sccm is passed through, holds It is 0~10 minute continuous, Mg layers of formation the first；

(3) close magnesium source, be passed through the silicon source, flow that nitrogen source, flow that flow is 65~75slm are 180~210sccm be 28~ The gallium source of 33sccm, growth thickness are the second non-doped layer of 0~20nm；

(4) silicon source and gallium source are closed, the nitrogen source that flow is 65~75slm and the magnesium source that flow is 950~1100sccm is passed through, holds It is 0~10 minute continuous, Mg layers of formation the 2nd；

(5) step (1), (2), (3) and (4) is repeated several times.

6. UV LED epitaxial structure as described in claim 1, which is characterized in that described AlN layers and N-type AlGaN One layer of transition zone is equipped between layer；The transition zone by several periods AlN/Al_aGa_1-aN (0.01 < a < 0.99) is super brilliant Lattice structure composition；The AlN/Al_aGa_1-aAlN's with a thickness of 1~5nm, Al in N superlattice structure_aGa_1-aN with a thickness of 1~ 5nm。

7. UV LED epitaxial structure as described in claim 1, which is characterized in that the active layer is by several weeks The quantum well structure of phase forms, and the quantum well structure includes Al_xGa_1-xN well layer and Al_yGa_1-yN barrier layer, 0 < x < 0.5, y ratio x It is big by 20% or more；

The Al_xGa_1-xN well layer with a thickness of 3~8nm, the Al_yGa_1-yN barrier layer with a thickness of 4~10nm.

8. UV LED epitaxial structure as described in claim 1, which is characterized in that in the N-type AlGaN layer, Si Doping concentration is 5E17~5E19atom/cm³, with a thickness of 0.5~2 μm.

9. UV LED epitaxial structure as claimed in claim 8, which is characterized in that in the p-type GaN layer, Mg mixes Miscellaneous concentration is 1E17~1E21atom/cm³, with a thickness of 0~200nm.

10. a kind of production method of the UV LED epitaxial structure as described in any one of claim 1~9, feature exist In, comprising the following steps:

One, it places the substrate into MOCVD device, is toasted 1~20 minute under the conditions of 900~1500 DEG C；

Two, temperature is adjusted to 900~1500 DEG C, the AlN layer that a layer thickness is 0.1~5 μm is formed on the substrate；

Three, temperature is adjusted to 900~1500 DEG C, forms the N-type AlGaN layer that a layer thickness is 0.5~2 μm, Si on AlN layer Doping concentration is 5E17~5E19atom/cm³；

Four, temperature is adjusted to 900~1500 DEG C, the quantum well structure in several periods is grown in N-type AlGaN layer, it is described Quantum well structure includes Al_xGa_1-xN well layer and Al_yGa_1-yN barrier layer, 0 < x <, 0.5,0.2 < y < 1, in each quantum well structure Al_xGa_1-xN well layer with a thickness of 3~8nm, Al_yGa_1-yN barrier layer with a thickness of 4~10nm；

Five, temperature is adjusted to 900~1500 DEG C, (1) is passed through nitrogen source, silicon source, gallium source, and growth thickness is the first of 0~20nm Non-doped layer；(2) silicon source and gallium source are closed, nitrogen source and magnesium source is passed through, continues 0~10 minute, Mg layers of formation the first；(3) it closes Magnesium source, is passed through nitrogen source, silicon source, gallium source, and growth thickness is the second non-doped layer of 0~20nm；(4) silicon source and gallium source are closed, is led to Enter nitrogen source and magnesium source, continues 0~10 minute, Mg layers of formation the 2nd；(5) step (1), (2), (3) and (4) is repeated several times, shape At p-type superlattices barrier layer；

Six, temperature is adjusted to 900~1500 DEG C, forms the p-type that a layer thickness is 0~200nm on p-type superlattices barrier layer GaN layer, Mg doping concentration are 1E17~1E21atom/cm³。